1. Field of the Invention
The present invention relates to a liquid crystal dispensing apparatus, and in particular, to a liquid crystal dispensing apparatus capable of dispensing an accurate amount of liquid crystal onto a substrate and distributing the dispensed liquid crystal onto the substrate.
2. Description of the Related Art
Currently, the development of various portable electronic equipment, such as mobile phones, personal digital assistants (PDAs), and notebook computers, require flat panel display devices having light weight, small size, and adaptability to portable electronic equipment. Various different types of flat panel display devices have been developed for these portable electronic equipment including liquid crystal displays (LCDs), plasma display panels (PDP), field emission displays (FEDs), and vacuum fluorescent displays (VFDs).
FIG. 1 is a cross sectional view of a liquid crystal display device according to the related art. In FIG. 1, an LCD 1 includes a lower substrate 5, an upper substrate 3, and liquid crystal material layer 7 arranged between the lower substrate 5 and the upper substrate 3. The lower substrate 5 is a driving element array substrate having a plurality of pixel regions formed on an inner surface thereof. A driving element, such as a TFT (thin film transistor), is formed within each of the pixel regions. The upper substrate 3 is a color filter substrate, and includes a color filter layer formed on an inner surface thereof for producing colored light. In addition, a pixel electrode and a common electrode are formed on the lower substrate 5 and the upper substrate 3, respectively, and an alignment layer for aligning liquid crystal molecules of the liquid crystal material layer 7 is coated on the lower substrate 5 and the upper substrate 3.
The lower substrate 5 and the upper substrate 3 are bonded to each other by a sealing material 9, and the liquid crystal material layer 7 is disposed therebetween. Accordingly, information is displayed by controlling an amount of light transmitted through the liquid crystal material layer 7 by driving the liquid crystal molecules with the driving element formed on the lower substrate 5.
A fabrication process of a liquid crystal display device can be divided into a driving element array substrate process for forming a driving element on the lower substrate 5, a color filter substrate process for forming a color filter on the upper substrate 3, and a cell formation process.
FIG. 2 is a flow chart of a liquid crystal display device fabrication method for forming the liquid crystal display device of FIG. 1 according to the related art. In step S101, a TFT array process is performed to include a plurality of gate lines and data lines (not shown) arranged on the lower substrate 5, thereby defining a plurality of pixel regions. In addition, a TFT is connected to the gate and data lines formed within each of the pixel regions to function as a driving element. Furthermore, a pixel electrode that contacts the TFT and drives the liquid crystal material layer 7 according to a signal applied through the TFT is formed by the driving element array process.
In step S104, red, green, and blue color filter layers and a common electrode are formed on the upper substrate 3 by the color filter process to generate colored light.
In step S102, a coating process includes forming an alignment layer on the lower substrate 3 to induce a surface anchoring (i.e., a pretilt angle and an alignment direction) to liquid crystal molecules of a liquid crystal material layer 7 formed between the upper and lower substrates 3 and 5. Then, the alignment layer formed on the lower substrate 3 is rubbed.
In step S105, an additional coating process includes forming an alignment layer on the upper substrate 5 to induce a surface anchoring (i.e., a pretilt angle and an alignment direction) to liquid crystal molecules of a liquid crystal material layer 7 formed between the upper and lower substrates 3 and 5. Then, the alignment layer formed on the upper substrate 5 is rubbed.
In step S103, spacers are uniformly dispersed on the lower substrate 5 to maintain a uniform cell gap between the upper and lower substrates 3 and 5.
In step S106, a sealing material 9 is coated onto the upper substrate 3.
In step S107, the upper and lower substrates 3 and 5 are bonded together under pressure.
In step S108, the bonded upper and lower substrates 3 and 5 are cut and processed to form a plurality of individual liquid crystal display cells.
In step S109, liquid crystal material is injected into each of the individual liquid crystal display cells via a liquid crystal injection hole. Then, each of the individual liquid crystal display cells is encapsulated.
In step S110, each of the encapsulated individual liquid crystal display cells is inspected.
FIG. 3 is a cross sectional view of a liquid crystal injecting apparatus according to the related art; In FIG. 3, a container 12 containing liquid crystal material 14 is disposed within a vacuum chamber 10, and a liquid crystal panel 1 is placed above the container 12. In addition, a liquid crystal panel mover (not shown) is disposed within the vacuum chamber 10 to move the liquid crystal panel 1 into the container 12, thereby making contact between the liquid crystal material 14 and a liquid crystal injection hole 16 of the liquid crystal panel 1. In general, this method is commonly referred to as a liquid crystal dipping injection method.
Then, the pressure within the vacuum chamber 10 is increased by supplying nitrogen (N2) gas into the interior of the vacuum chamber 10. Accordingly, the liquid crystal material 14 is injected into the liquid crystal panel 1 through the liquid crystal injection hole 16 due to a pressure difference between the liquid crystal panel 1 and the vacuum chamber 10. Then, after the liquid crystal material 14 completely fills the liquid crystal panel 1, the liquid crystal injection hole 16 is sealed by a sealing material and a liquid crystal material layer is formed inside of the liquid crystal panel 1. In general, this method is commonly referred to as a liquid crystal vacuum injection method.
However, the liquid crystal vacuum injection method is problematic. First, a total processing time for completely injecting the liquid crystal material 14 into the liquid crystal panel 1 through the liquid crystal injection hole 16 requires a significant amount of time. Generally, since an interval between the driving element array substrate (i.e., lower substrate 5 in FIG. 1) and the color filter substrate (i.e., upper substrate 3 in FIG. 1) of the liquid crystal panel 1 is about a few μm, a very small amount of liquid crystal material 14 per unit time is injected into the liquid crystal panel 1. For example, during fabrication of a 15 inch liquid crystal panel, total processing time for completely injecting the liquid crystal material 14 into the liquid crystal panel 1 may be 8 hours. Accordingly, fabrication efficiency of the liquid crystal panel 1 is low.
Second, a liquid crystal material consumption rate is very high. Compared to the amount of the liquid crystal material 14 placed into the container 12, the amount of liquid crystal material 14 actually injected into the liquid crystal panel 1 is very small. Moreover, when the liquid crystal material 14 is exposed to the atmosphere air or to certain gases, the liquid crystal material deteriorates. Furthermore, the liquid crystal material 14 deteriorates by the flow of impurities during contact with the liquid crystal panel 1. Thus, any of the liquid crystal material 14 that remains in the container 12 after injection into each liquid crystal panel 1 must be discarded. Accordingly, productions costs are increased.